PROJECT SUMMARY We propose to modernize in vitro toxicology testing to facilitate comprehensive evaluation of biological response profiles to engineered nanomaterials. To ensure that high-content evaluation of response profiles can be measured using human-relevant systems, our platform is based on organ-on-chip technologies presently used for pharmacology and in vitro disease models. We extend the capability of these systems by introducing novel exposure chips that recapitulate a variety of exposure routes and interface with existing organ chips. Nanomaterials administered through exposure chips to the underlying organs may elicit exposure route- dependent responses that we aim to quantify. Specific project aims include quantitative comparison of cardiac and airway tissue response profiles to engineered nanomaterials administered by direct exposure, through and endothelial barrier, through tissue engineered vasculature, or through a synthetic skin tissue. We focus on cardiac and airway organ models because they are established platforms that provide robust metrics of tissue viability, structure, and function, in response to pharmacological challenges. We extend the capabilities of these organ systems for nanomaterial toxicity testing with the addition of exposure chips. To model intravenous and topical delivery routes, successive variations of the exposure chips will recapitulate endothelial barrier properties and engineered dermal tissues with increasing fidelity. The proposed work builds on our laboratory?s expertise manufacturing and testing organ-on-chip in vitro toxicology platforms. Our team is a leader in this field, developing diverse organ models and exploring their interactions for drug screening and disease modeling applications. We have extensive experience fabricating modular organ chips and the proposed exposure chip will be broadly applicable to organ models beyond the original focus on cardiac and airway systems. Standardization of our organ chip manufacturing ensures that exposure chips can be interfaced with a broad and expanding arsenal or human organ models. Importantly, we expect this work will lead to future exposure chips encompassing an expanding number of delivery routes.